S.O.S distress calls, fantasy escape from trauma, and forever wars that need to be fought all swirl together in “Mayday,” a dreamy and surreal new feminist fairy tale and revenge film that debuted at the Sundance Film Festival this week. The feature-length filmmaking debut of writer/director Karen Cinorre, “Mayday” centers on Ana, a young woman who is mysteriously transported to an otherworldly and dangerous island.